I have the same problem on my laptop after loading the nvidia kernel module -- so something in the kernel is always uninterruptible, but it's not a process that I can see in userspace.

$ uptime; ps -L aux | awk '{ print $10 }' | sort -u 15:57:37 up 21 days, 22:49, 16 users, load average: 2.23, 1.61, 1.61 R+ Rl S S+ S< SLs SN STAT Sl Ss Ss+ Ssl T $ ps -L aux|awk '($10 ~ /^R/){ print }' rkeene 1025 1025 0.0 1 0.0 17980 2344 pts/10 R+ 15:57 0:00 ps -L aux $

Any processes stuck in D state?

There is one, a [hwrng] process, but I don't think that's it. It's also in D state on other virtual machines on the same host without this symptom.

(The process is probably from virtio-rng.)

I am assuming the guest (and host) kernels are sufficiently recent? I remember older kernels having a bug with load calculation. Does disabling Virtio-rng help? D state processes will cause rise in load average depending on NRCPUs.